Electromagnetic interference between a three-dimensional cardiac mapping system and an implantable cardioverter defibrillator

Abstract

Interference between implantable cardioverter defibrillators (ICD) and electromagnetic fields are of great concern due to the unfavourable influence on the function of the device [1, 2]. Electromagnetic interference in the medical environment has been described for several sources. The present report is the first to describe inappropriate shocks by an implantable cardioverter defibrillator caused by the external ultralow magnetic field emitter of a three-dimensional mapping system used in cardiac electrophysiology. A 77-year-old man with ischemic heart disease, complete heart block and severely reduced left ventricular ejection fraction was supplied with an ICD for secondary prevention of sudden cardiac death and cardiac resynchronisation therapy in 2006 which was later exchanged due to battery depletion (current implanted device: Cognis 100 P107, right ventricular electrode model: 0128; both Guidant/Boston Scientific, Natick, MA, USA). The patient was referred to the electrophysiological laboratory for the ablation of recurrent ventricular tachycardias. To facilitate the ablation procedure and to identify substrate that may trigger arrhythmias the three-dimensional mapping system Carto 3 (CARTO, Biosense-Webster, Diamond Bar, CA, USA) was used. Tachyarrhythmia detection of the ICD was disabled at the time of electrophysiological study commencement. It was enabled again (ventricular heart rates [ 125 bpm antitachycardia pacing only, [165 bpm anti-tachycardia pacing followed by cardioversion, [220 bpm defibrillation; right ventricular sensing at the nominal value of 0.6 mV) after a ventricular tachycardia arising from the left ventricular outflow tract had been ablated and all the catheters had been removed. Shortly after re-activation, the ventricular tachyarrhythmia detection the ICD administered two defibrillations in the absence of any tachyarrhythmia (Fig. 1). The inappropriate tachyarrhythmia detection was considered to be caused by the external ultralow magnetic field emitter (‘‘location pad’’) of the Carto 3 System which was inadvertently still active at that time. After switching off the Location Pad of the three-dimensional mapping system, no further shocks were observed and no other sources of potential electromagnetic interference were present in the electrophysiological laboratory. In addition, other reasons for oversensing, such as the detection of myopotentials or the presence of an insulation or conductor break were ruled out (signal amplitude 20,6 mV, pacing threshold 0,8 V at 0.5 ms, pacing impedance 681 ohms, all values remaining stable over time and being comparable with previous follow-up data). Catheter ablation has become a standard treatment for many arrhythmias especially in the context of failed pharmacological arrhythmia suppression [3, 4]. To facilitate the ablation procedure of ventricular tachyarrhythmias three-dimensional electroanatomical mapping system like the Carto system are commonly used. To the best of our knowledge, the reported case is the first to describe electromagnetic interference between the CARTO 3 system and an implantable cardioverter defibrillator. For non-fluoroscopic catheter navigation the ‘‘location pad’’ of the CARTO system—which is usually positioned under the catheterization table—creates an electromagnetic field of 5–50 lT at different frequencies. This electromagnetic field together with mapping/ablation catheters and a reference catheter equipped with miniature passive magnetic field sensors at their tip and a processing unit give A. Buiatti (&) H. Pavaci I. Deisenhofer C. Kolb Deutsches Herzzentrum Munchen, Klinik fur Herzund Kreislauferkrankungen, Faculty of Medicine, Technische Universitat Munchen, Lazarettstr. 36, 80636 Munich, Germany e-mail: elam4@libero.it